Sanding or rubbing attachment



Oct. 21, 1952 Filed July 26, 1947 S. D. ROBINS SANDING OR RUBBINGATTACHMENT 3 Sheets-Sheet 1 INV ENTOR SAMUEL DAVIS ROBINS TTORNEY Oct.21, 1952 s. D. ROBINS SANDING OR RUBBING. ATTACHMENT s Sheets-Sneet 2Filed July 26, 1'94? Ill/1111717111 INVENTOR SAMUEL DAVIS ROBINS wJA-rToRNEYs Oct. 21, 1952 s. D. ROBINS 2,614,369

SANDING 0R RUBBING ATTACHMENT Filed July 26, 194'? 5 Sheets-Sheet 3 23 2ARUWW l 7 I j I 24 4 27 26 I INVENTOR SAMUEL DAVIS ROBINS Patented Oct.21, 1952 Samuel Davis Robins; Lawrence, N. assignor to Du -Fast, IncaNew York, N; I}! acorporation inseam. my 26-, erial. resin 9 Glaims.

1. inv ntio rela es to. warn a d. a ull im r v ments n ub m a s forabilizing the m tion. or; s, vibrated bodies and especially providesanclaims.- v

The. nventio con sts as novel nests-i e: ru t nsi arrang m nts, .ea aatmo ments e s n s o n and des l de, he accompany n (Ira, inss referred.to here: in and constitu n a pa tner Q i lus pr f r d mb diment o theinvention, audio; ether wit the sscr nt n. ser o explain th r ple of hinven ion In th rubbing mashineart. as we as in th n nd sc en ng maehinart, it ha l n en common rac ice, o attu .,t1,1sse-Q e1 li e frame o heni em an f. a ing e un erba ance s qen, a aotuati ig' the name subs a iy a it e ter- :s av t S 24 1 x e and t s. a ob e o th s i v n n to n a aimmerse term ffl 'x e a mean i r' e en r ee l vi rate t p e odi s,

as are disclosed in U. s. Patents Nos. 2,032,382,

59 3940! 2,2 03%. a 0 3 9 and 23mm fer v erm ss e i thei n i n a r l syriq m m of the live frame to, take place, but they fail to e sec i nin in-th en e ha u h flexible; I

ns ne anno Pres i e a circu a orbit r Qllt the live frameunderconditions where out- 1 side, forces, may disturb the gyratoryorbits or may end to place heavy rotational loads on'the live frame as awhole, That is, they do not have position stability; Such outside forcesare commonly present in machines of all the classes mis ead h nei a dF1? 13?? deleterious fects. .4

Another object of this invention therefore is to, provide positionstabilization for eccentrically Yrated bodies Without recourse to theex- 1 pansiv'e mechanical stabilizing means which also are common inthese arts. Position stabilization comesunder one of three commoncategories, to wit, geared. eccentrics, as exemplified by U. 3. PatentNo, 2,395,537;' follower cranks (geared or not) as exemplified by U. S.Patent No. 2,247,- 993; and, pantographs, All of these accomplish not'.only the permissive function of the cheap flexible stabilizer but servethe added function of actually eliminating a general. rotation, eitheroscillatory or otherwise, of the live frame with respect to the deadframe. The first two types of stabilizers, namely, geared eccentrics andfol.-

plie throu h ailexib e liei Orbs, ail ents N s.- 32;3-82e 2.279930 n l sch ses new, so a irans" 9 tabil z ng the moti n at the] i e rame, be itscreen or rubb ng She is mpl yee, In most cases st bilizatiqn ,,,e' =tsgbyi oms m o flexible t bilizing me s arse bsien the n e oiua ioa flexibometime t e li e ame t the was massed p mitting lower cranks areobjectionable on at least three grounds. They involve rotating partswhichnot only involve extra cost but additional wear and al d v ses toxc ude rt.- h v a s requ e greatprecision to ensure perfect timedrelation to the master eccentric and this involves extra cost,Bantographhmeans of position stabilization is "to be preferred if-for noother-reason than because no precise. relation is called for in thessemb ri pa ts of the, tos p n r n t appli ati n he a s-m t the machine.

is thereforeianother object of this invention to siti a a .n graphprinciple, of 'gy ratory bodies through the provision" of flexibleelements only and without Occur, no ahaiaaaimoa for maintenance ormetrically disposed flexible stabilizers; slich abilization, on thepantolubrication will be needed and the device will be practicallyimmune to the presence of dirt, liquid, or abrasives.

A further object of this invention is to enable the utilization ofso-called "hand or portable general purpose drilling machine as thepower unit of an eccentrically vibrated portable or hand rubbingmachine, through the provision of the improved motion stabilizing meansof this invention. In this connection, it will be understood thatportable rubbing machines, as taught by the prior art, are many andvaried in type. In particular, the portable or hand type vibratorysanders are, in general, highly complex single purpose mechanismsproducible only at a high cost of manufacture. They embody relativelyhigh powered power units and the vibratory motion of the live frame orshoe is characterized by a relatively short stroke, e. g. inch or less,at a very high rubbing speed. On the other hand, general purpose, lowcost, hand drilling machines such as the conventional /4 inch electricdrilling machine commonly found in the home workshop are characterizedby a relatively low power, for example, a 1.5-2.5 ampere rating and by arelatively low chuck speed in the range, for example, of 1000 to 2500revolutions p r minute. This low chuck speed requires that if the drillis to be used to eccentrically vibrate a rubbing shoe, a long stroke ofthe rubbing shoe in the order of inch, for example, is required in orderto obtain a practically useful rubbing s eed. Position stab lization ofthrubbing shoe through the pee,

of known flexible stabilizing means s ch as the rubber skirts, rings andthe like, common in the art, would not do for this for, if the rubberskirt,

for example, were flexible enoi-gh to permit the required large strokeand yet notbreak down, it would allow the live frame or shoe to rotaterelative to the dead frame, or to deflect. Such rotation wouldinevitably result in overstressing of the flexible stabilizing means asdeflection ofit due to vibration, plus thatdue to rotation, builds up.On the other hand, if a rubber skirt stabilizer were used and madestrong enough so as not to go to pieces under the conditions of severestress reversal, then the heat loss would be large and the power drainon the hand drill would be too high, thus making use of the rubbing shoea practical impossibility On such drills. It is therefore another objectof this invention to provide a new, useful and improved rubbing machineparticularly adapted for use in surface sanding in the woodworking andallied arts, and to provide a new and useful rubbing attachment for lowcost electric hand drills, to the end that the home workshop inparticular may be provided, through the medium of such attachment, withboth drilling machine and rubbing machine in one low cost, dual purposetool.

In the accompanying drawings in which like numbers refer to like partsthroughout the several views:

Figure 1 is a perspective view of a preferred embodiment of thisinvention as applied to a sander attachment for low cost electric handdrills, the View showing the hand drill (less chuck) and the rubbingattachment, including actuating eccentric, in exploded relationship,ready for assembly into a complete rubbing machine unit, the drill anddetached chuck of the drill being shown in dash-dot outline;

Figure 2 is a view in vertical section along the medial longitudinalplane of the embodiment shown in Figure 1, the view showing the rubbingattachment and hand drill in assembled relat onship with the rubbinghead in thereby displaced position, the hand drill (less chuck) beingshown in dotted outline;

Figure 3 is a view in top plan of the embodiment shown in Figure 1omitting the driving eccentric for the rubbing shoe in order to exposeunderlying parts, the rubbing head being shown in normal undisplacedposition;

Figure 4' is a view in side elevation of the embodiment of Figure 1;

Figure 5 is a view in end elevation of the embodiment shown in Figure 1;and,

Figure 6 is a fragmentary view in section of a modified form ofeccentric actuating means and its connection to the rubbing shoe of theembodiment of Figure 1.

In general, the motion of an eccentrically vibrated body may bepositionally stabilized in accordance with this invention through theprovision of a novel system of stabilizing link members flexiblyconnecting thelive frame to the dead frame and permitting a high degreeof freedom of movement of the live frame in translation while preventingits rotation relative to the dead frame 1 In, accordance, with thepreferred illustrative embodiment of this invention, an intermediateframe is 'jdisposed between the live frame and the dead frame and isflexibly connected to the respective frames by separate systems ofstabilizing link members, disposed at right angles to each other.

The system of dead frame link members operates to prevent any rotationof the intermediate frame relative to the dead frame while permitting ato-and-fro substantially linear motion of translation of theintermediate frame substantially parallel to the dead frame, in onedirection only. The system of live frame link members likewise operatesto prevent any rotation of the live frame relative to the intermediateframe while permitting a to-and-fro substantially linear motion oftranslation of the live frame substantially parallel to the intermediateframe, in a direction at right angles only to the permited direction ofmovement of the intermediate frame. Thus, relative rotation of the liveframe and the dead frame is wholly prevented by the torsional rigidityof the stabilizing system as a whole while the respective motions of thelive frame and intermediate frame may be compounded to cause the liveframe to move in a motion of curvilinear translation relative to thedead frame.

Means are provided for actuating the live frame through the applicationthereto of a radial force of preferably constant magnitude but ofconstantly changing direction to impart thereto a motion of translationwhich is preferably circular.

Advantageously, moreover, the dead frame may be constructed. andarranged for releasable locking engagement with the frame, motor housingor other fixed .portion of a portable electric drilling machine so as toprovide a rubbing attachment combinable with the drilling machine toform the novel and improved rubbing machine of this invention. In suchcase, the usual chuck of the drill is removed and is replaced by theactuating means above-mentioned for engaging and eccentrically vibratingthe live frame in statically and dynamically counter-balancedrelationship. In such case also, the live frame is suitably fashionedtd' serve as a rubbing shoe or head having provision for releasablysecuring thereto a layer of rubbing material such, for example, as asheet of sand Paper or other abrashe material, by." means-lot certain.novel. quick release. fastening devices. of, invention.

It will be nnderstoodthatthe foregoinaweeneral description and: the;following detailed 'de scription as well are exemplary and explanatoryof the invention but are not: restrictive thereof.

Referring nowmore particularly to the em bod-iment of this inventionshown. in .Eigures; 1 to 5 of the accompanyingdrawings, a dead frame isdisposed in spaced, parallel or substantially:

I 6; but ofconstantlychanging direction, substantiall-y :at its.center-of-gravity to. impart to, the live framev a motion of translationwhich :maybe re.- ciprocatory but is preferably an orbital motionoficircular translation. The actuating means asv here preferablyembodied comprises a crank member i0 having a stub shaft Ii adapted tobe-connected to a suitable prime mover, a crank pin l2 :at one side ofthe stub shaft, and a counterweight-portion 13 at the opposite: side.

The 'crankmember NJ as shown in Figure 2, is journalled to the liveframe. I by means of suitable anti-friction journal means such as theball-bearing unit I 4. in whose inner raceway the crank pin 12 is snuglybut not tightly received. The tip portion of the crank pin is of aconfiguration which is preferably spherical as shown'to permit a degree.of self-aligning rocking action of the crank pin in the innerraceembodied are each constituted by :a short strip of flexible materialsuch, for example, as power belting material capable, of under oing apracticallyinfinite number of flex stress reversals over a pulley ofsmall diameter, e. g. f inch, without failure.

way .of :the bearing unit so that any minor angular displacement of .thelive frame will not be'transmitted directly to the crank member.Moreover, the crank portion l2 and the journal unit l4are disposed andarranged with respect to the. live. frame so that the radial thrustforce of the crank portion will be applied to the i live. framesubstantially in the horizontal plane The intermediate. frame. 3 as herepreferably embodied is of rectangular or substantially rectangular shapeand comprises parallel side and end rails 6- and 1, respectively,preferably of metal, forming a rigid yet light weight open.

structure. I

Each of the end rails 1 serves as a terminal fitting fashioned toreceive and firmly grip an end of one of the link members 4 whose otherend is likewise received and firmly gripped by one of a pair of terminalfittings 8 each, likewise fashioned for the purpose and fixedly securedto the dead frame I at ends in parallel relation to each other and tosaid end rails 1 so that the link members 4 will normally parallel eachother at the frame ends. Thus, by reason of the flexible nature of thelink members 4 and their parallel arrangement, the intermediate frame 3is capable of substantially linear to-and-fro movement parallel to thedead frame in one direction only, but is substantiallycompletelyimmobilized against rotation relative thereto.

Each of the side rails 6 also serves as a terminal fitting fashioned toreceive and firmly grip an end of one of the link members 5 whose otherend is likewise received .and firmly gripped by one of a pair ofterminal fittings 9 each likewise suitably fashioned for the purpose andfixedly secured to the live frame 2 at its sides in parallel relation toeach other and to said end rails I so that the link members 5 willnormally parallel each other at right angles to the link members 4.Thus, by reason of the flexible nature of the link members 5 and theirparallel arrangement, the live frame 2 is capable of substantiallylinear to-and-fro movement parallel to both the intermediate frame 3 andthe dead frame I in one direction only which is at right angles to thepermitted direction of movement of the interlive of thecenter-of-gravity of the live frame and preferablyso as to makev thecenter-of-gravity andcenter-of-actuation of the live frame closelycoincident, within practical limitations of construction.

- The counterweight portion [3 of the crank member is likewise of 'amass and arrangement affording optimum static and dynamic balance of thecounterweight portion and live frame about the rotational axis of thestub shaft II.

} Moreover, in order to minimize dynamic un crank pin side of'the crankmember so as to be frame 2 throughv the a plication thereto of a radialforce of preferably constant magnitude balance caused by the creation ofa couple tending to cause whipping of the stub shaft ll, the

counterweight portion is concentrated on the close to the live-framesubstantially in the bearing plane.

It will be evident that the rotation of the crank member I 0 on therotational axisof the stub shaft I'l coupled with the action of thestabilizing system will impart to the live frame 2 a motion oftranslation in a circular orbit, assuming the dead frame I to be heldfixedly. The diameter of the orbit will obviously'be determined by thethrow of the crank portion l2, and in the ap plication of this inventionas a rubbing attachment for portable electric drilling machines, a throwof approximately one quarter of an inch has been determined to beadvantageous in order to. obtain an efiicient rubbing speed.

For such application and in accordance with the preferred embodiment ofthis invention as illustrated in Figures 1 to 5 inclusive, the deadframe I is suitably constructed for releasable attachment to the barrel(motor housing) or other fixed portion of the drilling machine.Preferably, the dead frame, which may be referred to for convenience asthe attaching head,

is provided with an aperture 16 designed to driving spindle of thedrill.,: as indicated in Figure 2'.

- 'Means are provided for releasably firmly securing the attaching headI of the rubbing attachment to the drill. As here preferably embodied, apair of fixed positioning lugs I9 carried by the attaching head I at oneend of the aperture l6 are disposed to engage the barrelof the drillunit I1 at spaced points preferably in suitable apertures such as theseries of cooling air ventilating apertures 2|] disposed cir'cumferentially of the drill motor housing. 'A movable clamping member 2|disposed in the aperture I6 at its opposite end is pivotally supportedby and at one end of a clamping screw 22 which is in turn threadedlyreceived in a lug 23 integral with the attaching head Other positioninglugs 24 integral with the movable clamping member 2| are disposed toengage the drill unit H at spaced points as in the ventilating apertures20. The clamping member 2| is of a configuration complementary to thesurface portion of the drill housing which it is adapted to engage, asis the attaching head I at the opposite end of the aperture l6. bers 25preferably integral with the clamping member 2| extend outwardlytherefrom in slid-' ing engagement with the attaching head and serve tomaintain the clamping member in a generally upright position withrespect to the at-' taching head. The pivotal connection of the clampingmember to the clamping screw enables the former to accommodate itself toany slight irregularities in shape of the drill housing.

It will be apparent from the foregoing that the drill unit is adapted tobe clamped in the aperture It between the attaching head I at one end ofthe aperture I6 and the screw actuated clampingmember 2| at the otherend. The positioning iugs I9 and 24 serve precisely to locate therubbing attachment vertically as viewed. in Figure 2 as a whole relativeto the drill unit so that the crank pin I2 will be correctly positionedin the bearing unit I4 in the assembled relationship. It will beapparent also from a consideration of Figure 2, that in assembling thedrill unit and rubbing attachment, a lateral displacement of the-liveframe or rubbing head I in an amount equal to the throw of thecrank'member I will be necessary. This displacement is shown in Figure 2wherein the stabilizing link members 4 are shown in an extreme flexedposition. Moreover,

although the terminal fitting 8 of the link mem-' bing attachment, ashere preferably embodiedv comprises a relatively stiff flat member 28forming a pressure plate of rectangular contour in plan, as seen inFigure 3, having upstanding marginal stiffening fianges 28 at itsopposite sides and curved upwardly and inwardly turned end portionsforming sockets 3B in which the ends of a sheet 3| of sand paper orother rubbing material are adapted to be removably secured.Reinforcement of the plate member 28 is efiected by a stiffening member32 extending preferably from side-to-side of the pressure plate 28 andapertured to fit snugly over and around the bearing socket member I upona circumferential Guide mem marginal base portion 33 providing abroadand ample support for the bearing socket IS on the pressure'plate 28.Fastening means 34 serve to hold the bearing socket in fixed positionbetween the stiffening plate 32 and pressure plate 28 centrally of thelatter. The stiffening plate 32 is offset at its opposite ends intoengagement with the pressure plate 28 to which it is fixedly secured. Itwill be noted that the stiffening plate by reason of its spaced relationto the pressure plate 28 between its ends forms a light but strongbox-like structure offering substantial resistance to flexing underload. Moreover, the stiffening member 32 provides a foundation orplatform to which the terminal fittings 9 of the link members 5 arefixedly secured preferably by means of short spacing members 35 disposedbetween and secured to the stiffening plate 32 and the anchor members 9at the respective opposite ends of the link members 5.

In accordance with this invention'also, means are provided at each endof the rubbing head for readily releasably securing the layer 3| ofrubbing material to the rubbing head. The embodied securing means isdesigned to hold the rubbing material securely in substantially tautfashion between the ends of the shoe while enabling it to be replacedquickly for replacement by a simple yet fast-actingfastening device.tening means is disposed at'each end of the rubbing shoe, the fastenersbeing identical in construction, mounting and arrangement and as herepreferably embodied each comprises an actuating' lever member 36 mountedbetween and upon brackets 31 fixedly secured to the stiffening plate 32,for pivotal movement on bearings 38 toward and away from the latter.Side flanges 89 of the lever member '36 provide pivot bearings 49 forthe respective opposite ends of a spring-wire retaining member 4| whichis preferablysubstantially coextensive in width with the pressure plate28 and is adapted to be lodged substantially snugly in the pocket orrecess 39 formed by each inturn'ed end portion of the pressure plate, asis bestshown in Figure 2. The position of the pivot bearings 40 in theside flanges 39 is one ensuring that in the locked position of theactuating lever member 36, as shown in Figure 2, the axis of theco-axial bearings 40 will lie between the pressure plate 28 and theinclined equilibrium reference plane connecting socket 30 with the axisof the bearings 40. It will be apparent that, as the right hand levermember, for example, in Figure 2 is rotated in a counter-clockwisedirection, the distance between the axis of the bearing '40 and the baseof the socket 30 will be shortened, thus placing the spring-wireretaining member ti under further compression until the rotational axisof bearing 48- lies in the equilibrium reference plane. Further rotationwill result in the compressed spring-wire member, suddenly forcing thelever member through a substantially-greater angle into fully. releasedposition, permitting the spring member to bedisengaged entirely from thelocking recess for replacing therubbing material. automatic snap-actionlocking of the spring member in position as the bearing points move pastthe reference plane in a clockwise direction as viewed in Figure 2. Alayer 42 of soft rubber or other suitable resilient material ispreferably bonded to the under surface of the pressure plate so as toobtain a more uniform distribution of the rubbing pressure in operation.

In the operation of the embodiment of this in- One such fas-' Thereverse operation will result in an I garage 'vention hewn pi fi ure t inii i fi f si attachment for portable electric drills; :the rotation ofthe counterpoise crankmember '1 o by the drill motor throu'gl'i' thetorque"- applied 'tafthe stub shaft H will result in the rubbinashoeibeing set'in a high speed motion'fof 'circular translation in the planeof the rubbing 'face. As previously noted, the'--"throw pf" the crankpin' I2 is desirably large, e. g. one uarter inch; in prde'rf to obtaina h'ignrubbing' speed in? the orbit "of movement; It will'be apparent,howeverjthat' the. highly flexible link members will 'oifer little re-'sistance to fiexure, thusfplacing substantially no objectionable loadonxthe" power unit'jfrom this cause. At the same time, there can"benorelative rotation of the ru ling sho'e relative to; the power unitand thereis hence no overstressing of the stabilizing link membersaswould occur were stress .due to deflection inrotation added'to thatdue to VibraA'Jon."Moreover, the "exertion of greater rubbing pressureonone'end ofthe rubbing shoe than on the other'cannot result 'i nastopping or diminishing of theextent'of sideways' motion of the end atwhich the pressure isincreased. Such "a change would impose undesir ablyheavy loads on aflow 'powe'r' hand drill were the change permitted sincea stopping of the sideways motion of the toe for example would doublethe Sideways motion of the heel, thus doubling the fiexuralstress. Nosuch action is possible with the flexible pantograph stabilizing meansof this invention; It will also'be apparent that by reason of theconstruction of thestabilizing means, the parts will require no oilingexcept for the bearing unit and the presence of abrasive materials willnot result in wear of the stabilizing members, whose life is for allpractical purpc'ses, infinite.

In Figure 6 there is depictediafl modified ram of eccentric connectionbetweerithe crankimerm ber Ill and rubbing shoe ,L 'llhe. construct onserves further to'reduce thevertical spac tion, l3 of the crank memberand of the rubbing shoe i along the rotational axis. of? the stubsh'aftl I, thus further reducing the. couplc 'action-therefl betweenand-obtaining a closer approximation to complete dynamic equilibriumshown',:; the crank member ID' is recesseditof receive thebeari ,ingunit l4 which fits over a generally cylindrical pin 43 having'an annularmounting fiangeportion 44 fixedly secured with reference to the rubbingshoe between the stiffening plate 32 and the pressure plate 28. Thecrank action remains the same as in the embodiment of Figure 2, but theplacing of the counterweight portion closer to the rubbing head reducesthe magnitude of the couple tending to whip the shaft II and subject thebearings of the prime mover I! to side thrust.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chief advantage.

What is claimed is:

1. A rubbing device for attachment to hand drilling machines having adrill body, said device comprising an attaching head having an openingto receive said drill body and adapted to be releasably clamped to thedrill body; a rubbing head; an intermediate rigid frame element betweensaid attaching head and said rubbing head;

separate sets of flexible link members flexibly connecting saidintermediate [frame element to said rubbing lheadand to said attachinghead, respectively;thejlinkmembers of the respective sets ibeiiig.parallel to each other and the link members of 1 ones'et being atsubstantially right anglesgt'o the' link members of the other wherebytranslatory but notmtarymotion of said rubbing head relative to-saidattaching headis permitted; and, .a crank membertobe conneeted to androtated by the driving shaft of said drilling machine'forimpartingmotion to said rubbing head said .crank member beingljoiirnalledto saidrubbin'ghead on an axiseccentric tothe a xis of said driving shaft whenthe drilling machine is in said opening. I

2. A rubbing device for attachment to hand drilling achinesxhavingdrillbody, said device comprising'an attaching headhaving an openingtoreceive said body and adapted to be releasably clamped tothe drillbody; means on said attachinglhead movable into and out of a fixedposition of engagement withsaid body for clamping said head to saidbod-y; arubbi'ng'head articulated to said attaching head by separatelink systems each comprised of parallelly extendingfiexible strips}. acrank member to be removably connectedto' sai'd' drilling machine forrotation thereby, said member havingjournalengagement withsaid'rubbinghead substantially at its center-ofgravity on an axiseccentric to the rotational axis of the crank-and having a counterweightportion for "statically and dynamically balancing said rubbingheadrelative to said rotational axis;

31 The device comprisinga live frame; a dead frame; anintermediateframe;a system of par: allell-y' extending .fiexible stripsconnecting saidintermediate. frame to said dead frame a separate system ofpa-rallellyextending flexible strips connecting said intermediateframe to said liveframe, the. strips of each said system being adapted fto yield-"indirections: normal to the plane;

of said live frame'and' the strips-of one saidsystem being disposedatsubstantially right angles to thestri'ps of; the other; and, meanstoberois adapted to be inserted; movable clamping means carried by saidhead for fixedly securing said machine in said aperture to said head; arubbing head articulated to said attaching head by separate link systemseach comprised of parallelly extending flexible strips; and, means to beremovably attached to and driven by said machine, for actuating saidrubbing head.

5. A rubbing device for attachment to hand electric drilling machineshaving a body provided with a handle end and a driving shaft end, saiddevice comprising an attaching head adapted to encompass the body ofsaid drilling machine between its handle end and its driving shaft end;-clamping means for releasably securing said head to said body in adetermined fixed position between said ends; a rubbing head having ajournal bearing located centrally thereof; a crank member having a stubshaft adapted for operative engagement with and rotation by the drivingshaft of said machine on an axis eccentric to the rotational axis ofsaid journal bearing andfixed relative to said attaching head, saidcrank member having a crank pin journalled in said journal said frame tosaid rubbing head; whereby a gyratory motion may be imparted to saidrubbing head by said drilling machine while rotation of said rubbinghead relative to said attaching head is prevented.

6. A device for attachment to hand electric drilling machines having abody provided with a handle end, a driving shaft end and ventilatingapertures intermediate said ends, said device comprising an attachinghead adapted to encompass the body of said drilling machine in adetermined fixed position between its handle end and its driving shaftend; means on said attaching head movable into and out of a fixedposition of engagement with said ventilating apertures in saiddetermined fixed position of said attaching head on said body, forclamping said head to said body; a movable head carried by saidattaching head; and, means to be removably attached to and driven bysaid machine for actuating said movable head. i

7. In the combination of an electric motor and a rubbing device, theimprovement comprising an attaching head connected to said motor; arubbing head; an intermediate rigid frame element between said attachinghead and said rubbing head; separate sets of flexible link membersflexibly connecting said intermediate frame element to said rubbing headand to said attaching head, respectively, the link members of therespective sets being parallel to each other and the link members of oneset being at substantially right angles to the link members of the otherwhereby translatory but not rotary motion of said rubbing head relativeto said attaching head is permitted; and, a crank member to be connectedto and rotated by the driving shaft of said electric motor for impartingmotion to said rubbing head, said crank member being journalled to saidrubbing head on an axis eccentric to the axis of said driving shaft.

8. A rubbing device in accordance with claim 4 wherein the movableclamping means for securing the drilling machine to said attaching headinclude means movable into and out of a fixed position of engagementwith the ventilating apertures present on said drilling machines.

9. A rubbing device for attachment to hand drilling machines having adrill body, said device comprising an attaching head having an openingto receive said drill body and adapted to be releasably clamped to thedrill body; a rubbing head; an intermediate rigid frame element betweensaid attaching head and said rubbing head; separate sets of link membersflexibly connecting said intermediate frame element to said rubbing headand to said attaching head, respectively,

" but not rotary motion of said rubbinghead relative to said attachinghead is permitted; and, a crank member to be connected to and rotated bythe driving shaft of said drilling machine for imparting motion to saidrubbing head, said crank member being journalled to said rubbing head onan axis eccentric to the axis of said driving shaft when the drillingmachine is in said opening.

SAMUEL DAVIS ROBINS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 681,254 Northway 1 Aug. 27, 1901900,313 Schutz Oct. 6, 1908 1,469,926 Kirkegaard Oct. 9, 1923 1,482,294Fraser Jan. 29, 1924 1,520,631 Dey et a1 Dec. 23, 1924 1,558,167 HerrickOct. 20, 1925 1,785,065 Aborn Dec. 16, 1930 1,824,559 McCabe Sept. 22,1931 1,868,507 Roos July 26, 1932 2,270,309 Kehle Jan. 20, 19422,276,534 Burleigh Mar. 17, 1942 2,301,853 Cannon Nov. 10, 1942'2,335,614 Spievak Nov. 30, 1943 2,370,864 Krieger -.Mar. 6, 19452,500,850 Miller Mar. 14, 1950

